Known from EP-A 0242550 is a high-pressure cleaning unit in which a wobble body is mounted in a rotationally fixed manner on the drive shaft of an electric motor. Additionally provided is a wobble plate arranged at an incline to the drive shaft, the front side of the wobble plate driving several pistons positioned parallel to the axis of rotation of the drive shaft. An axial-groove ball bearing is positioned between the wobble body and the wobble plate. The axial-groove ball bearing is provided with ball grooves and balls rolling in the grooves. The increasing demands on the performance of such high-pressure cleaning units require an increase in the rotary speed of the drive shaft. At elevated rotary drive speeds, substantially increased centrifugal forces act on the balls of known axial-groove ball bearings so that there is a danger that the load distribution on the races will shift from one of uniform loading to a loading of the outer edge areas of the ball grooves. The associated wear and possibly reduced rollability of the balls is undesired. In addition, there is the danger that as a result of the increased edge loading, the races will become deformed such that the balls will be slung radially from the race path.